A boy has been attacked by a shark in Sydney’s east and is in a critical condition after suffering serious injuries to both legs.

The boy, believed to be aged about 12, was pulled from the water at Shark beach, in the eastern suburb of Vaucluse, on Sunday afternoon.

He was treated at the scene by first responders with tourniquets, New South Wales police said.

Emergency services were first called to the harbourside beach at about 4.20pm, police said.

Intensive care and aeromedical units, including the CareFlight helicopters, also responded, NSW Ambulance said.

The boy was transported to the Sydney Children’s hospital in Randwick for treatment of his critical injuries, an ambulance spokesperson said.

Shark beach was closed and police advised swimmers to avoid swimming in the water.